1. Field of the Invention (Technical Field)
The invention relates to artificial muscles and more particularly to artificial muscles actuated by a hydrogen gas as a working fluid and metal hydrides as a hydrogen sponge and can be operated both electrically and thermally.
2. Background Art
Materials and devices that can mimic biological muscles and thus be considered as artificial muscles have been discussed in the pertinent literature. There are prior art artificial muscles using ionic polymers as disclosed in M.
Shahinpoor, Y. Bar-Cohen, J. Simpson, and J. Smith, xe2x80x9cIonic Polymer-Metal Composites (IPMC""s) As Biomimetic Sensors, Actuators and Artificial Muscles-A Reviewxe2x80x9d, Smart Materials and Structures Journal, Vol. 7, pp. R15-R30, (1998); M. Shahinpoor, xe2x80x9cIonic Polymer Metal Composite As Biomimetic Sensors and Actuatorsxe2x80x9d, in Polymer Sensors and Actuators, edited by Y. Osada and D. DeRossi, Springer-Verlag Publishing, Springer, Berlin-Heidelberg, pp. 325-360, (1999).
In addition, shape memory alloy artificial muscles have been disclosed in M. Shahinpoor, xe2x80x9cFibrous, Parallel Spring-Loaded Shape-Memory Alloy (SMA) Robotic Linear Actuatorsxe2x80x9d, U.S. Pat. No. 5,821,664, issued Oct. 13th, 1998; G. Wang and M. Shahinpoor, xe2x80x9cDesign, Prototyping and Computer Simulation of A Novel Large Bending Actuator Made with A Shape Memory Alloy Contractile Wirexe2x80x9d, Smart Materials and Structures Journal, Vol. 6, No. 2, pp. 214-221, (1997); G. Wang and M. Shahinpoor, xe2x80x9cDesign for Shape Memory Alloy Rotatory Joint Actuators Using Shape Memory Effect and Pseudoelastic Effectxe2x80x9d, Smart Materials Technology, Edited by W. Simmons, Ilhan Aksay and D. R. Huston, SPIE Publication Vol.3040, pp. 23-30, (1997); and G. Wang and M. Shahinpoor, xe2x80x9cA New Design for A Rotatory Joint Actuator Made with Shape Memory Alloy Contractile Wirexe2x80x9d, J. Intelligent Materials Systems and Structures, Vol. 8, no. 3, pp. 215-219, March (1997).
Liquid crystal elastomer artificial muscles are discussed in M. Shahinpoor, xe2x80x9cElectrically-activated artificial muscles made with liquid crystal elastomersxe2x80x9d, paper no. 3987-27, SPIE Smart Materials and Structures Conference, New Port Beach, Calif., Mar. 5-9, (2000).
Other types of artificial muscles are discussed in U.S. Pat. No. 5,250,167 entitled Electrically Controlled Polymeric Gel Actuators; and U.S. Pat. No. 5,389,222 entitled Spring-Loaded Ionic Polymeric Gel Linear Actuator.
However, none of the prior art discloses metal hydride artificial muscles.
In accordance with the present invention there is provided a method and apparatus for using metal hydrides for an artificial muscle system. The preferred metal hydride artificial muscle comprises an expandable bladder, at least one metal hydride specimen encased within the expandable bladder and an apparatus to heat the at least one metal hydride. The preferred expandable bladder also comprises a collapsible bladder. The preferred expandable bladder comprises a hermetically sealed bladder. The expandable bladder can further comprise at least one actuator arm affixed to at least one part of said expandable bladder and can also comprise spring loading the at least one actuator arm. The preferred at least one metal hydride specimen comprises encapsulated particles within the at least one metal hydride specimen. The preferred encapsulated particles comprise an encapsulated material comprising a thermally conductive medium. The preferred apparatus to heat the at least one metal hydride comprises a controller. The preferred controller comprises a temperature sensor feedback loop. The controller can also comprise a microprocessor. The apparatus to heat the at least one metal hydride specimen can comprise an electric Joule heater. The preferred apparatus to heat the at least one metal hydride specimen comprises a heater to heat the at least one metal hydride specimen above at least one critical temperature. The apparatus to heat the at least one metal hydride specimen can further comprise an apparatus to cool the at least one metal hydride specimen. The preferred apparatus to cool the at least one metal hydride specimen comprises an apparatus to cool the at least one metal hydride specimen to below at least one critical temperature.
The preferred method for actuating an object with a metal hydride artificial muscle comprising the steps of providing at least one metal hydride specimen in an expandable bladder, affixing at least one part of the expandable bladder to an actuator arm and heating the at least one metal hydride specimen. The step of heating comprises heating the at least one metal hydride specimen above at least one critical temperature. The preferred method further comprises the step of cooling the at least one metal hydride specimen. The preferred step of cooling comprises cooling the at least one metal hydride specimen below at least one critical temperature. The step of heating preferably comprises controlling a heater. The step of controlling comprises sensing a temperature of the at least one metal hydride and feeding the sensed temperature to the controller. The method can also comprise the step of spring loading the at least one actuating arm. The preferred step of providing at least one metal hydride specimen comprises encapsulating particles within the at least one metal hydride specimen with a thermally conductive medium.
The preferred metal hydride artificial muscle for biomedical and robotic applications comprises an expandable bladder with a first end affixed to a first portion of a body and a second end affixed to a second portion of a body, at least one metal hydride specimen encased by the expandable bladder and an apparatus for heating and cooling the at least one metal hydride specimen.
The preferred metal hydride artificial muscle for hydrogen gas aided take off, flying and landing of an object, comprises a bladder, at least one metal hydride specimen encased by the bladder, and an apparatus for heating and cooling the at least one metal hydride specimen.
The preferred metal hydride artificial muscle joint power augmentation system for external assistance of a person comprises an expandable and collapsible bladder with a first end affixed to a first portion of the area to be augmented and a second end affixed to a second portion of the area to be augmented, at least one metal hydride specimen encased by the expandable and collapsible bladder and an apparatus for heating and cooling the at least one metal hydride specimen. The joint power augmentation system can comprise a joint power augmentation system for astronaut space suits.
A primary object of the present invention is to provide a new family of artificial muscles capable of actuating with a broad range of applications.
Yet another object of the present invention is to provide electrical and thermal robotic control capabilities.
Yet another object of the present invention is to mimic biological situations that require high force, power, and velocity responses.
A primary advantage of the present invention is that it provides biological-like smooth operation capability with long stroke capabilities of actuation along with large forces.
Another advantage of the present invention is that it is noiseless and vibrationless.
Yet another advantage of the present invention is that the functioning mechanism is the simultaneous hydrogen absorption/desorption and can lead to a buffering effect preventing sharp power surge or shock loads.
Another advantage of the present invention is that in selecting an appropriate hydride, the desired operating pressure can be easily obtained.
Another advantage of the present invention is that it can also provide a large actuation-displacement.
Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.